A common manufacturing operation is creating a cylindrical recess (a round hole) of a precise diameter at a precise location in a work piece. A boring tool (also known as a cutting tool or a boring bit) mounted in the spindle of a computer-controlled, rotating, axially moving milling machine is commonly used for the operation. The boring tool is a metal cylinder having an end for mounting in the spindle of the machine and a head. The head has one or more recesses on the outer surface of its boring end for mounting cartridges holding replaceable cutters (also known as cutting inserts or teeth). Both the radial (perpendicular to the axis of rotation) position and the axial (parallel to the axis of the rotation) positions of the cutters are important.
Cutters are typically made of carbide and eventually wear with prolonged use. As a result of the wear, the recesses created in the work piece would eventually decrease slightly in diameter. In operations where the diameter of the recess must be maintained precisely, it is necessary to periodically either replace the cutter or adjust its position. Having the ability to quickly and easily adjust the position of the cutter is highly advantageous because it minimizes the down time and cost.
Boring tools having a single, adjustable cutter are widely used. The adjustment is typically made with a screw that passes radially through the boring tool and engages the cartridge holding the cutter. The primary disadvantage of boring tools having a single cutter is that they are relatively slow.
Boring tools having two opposed cutters are also known. Other things being equal, a boring tool with two cutters creates a recess twice as fast as a boring tool with only one cutter. Several boring tools have been disclosed that have two opposed cutters whose radial positions are adjustable. For example, Muendlein et al., U.S. Pat. No. 5,188,490, Feb. 23, 1993, disclose a boring tool with two opposed cutters whose radial positions are adjusted by radial movement of two tapered rams. Stojanovski, U.S. Pat. No. 6,406,225, Jun. 18, 2002, discloses a boring tool with two opposed cutters whose radial positions are adjusted with a single radial adjusting screw. Pang, Chinese Pat. No. 102335759, Feb. 1, 2012, discloses a boring tool with two opposed cutters whose radial positions are adjusted with a radial double-headed bolt.
Boring tools having three or more cutters are also known. Boring tools with cutters whose radial positions are adjusted by axial adjustment of one or more wedge-shaped members are known. For example, Herrmann, U.S. Pat. No. 4,133,399, Jan. 9, 1979, discloses a boring tool having three or five cutters, each of whose radial position is adjusted by axial movement of an adjusting wedge. As the wedge moves further inward axially, it pushes the cartridge (or the cutter itself) further outward radially. Kanahoshi, Japanese Pat. No. 2006150535, Jun. 15, 2006, discloses a boring tool with five cutters, each of whose radial position is adjusted by axial movement of an adjusting wedge. Jiang, Chinese Pat. No. 203076611, Jul. 24, 2013, discloses a boring tool with three cutters whose radial positions are simultaneously adjusted by the axial movement of a single conical adjusting block.
While these multiple-cutter boring tools use adjusting wedges to adjust the radial positions of the cutters, the axial positions of the cutters are not easily adjusted. Accordingly, there is a demand for a boring tool that has one or more cutters whose radial and axial positions are both easily adjusted.